Use UMF_LEVEL_ZERO_INCLUDE_DIR in an example

[lukaszstolarczuk]

We could add in any of the examples, usage of the UMF_LEVEL_ZERO_INCLUDE_DIR variable. Currently we test it only via UR build.

Ref. #872

[vinser52]

Why not to extend regular testing?

[lukaszstolarczuk]

examples are part of our regular testing 😉

I saw this like - either we set it up in some CMake (like for standalone examples) or add it in (every?) CI workflow file, which might be too much...? While resolving this issue we can iterate these (and other) scenarios and pick the best one.

[vinser52]

I saw this like - either we set it up in some CMake (like for standalone examples) or add it in (every?)

L0 tests are run only on L0 runners. So we do not need to add such scenario to every CI workflow, just to the L0 one.